diff --git a/devscripts/generate_aes_testdata.py b/devscripts/generate_aes_testdata.py index e3df42cc2..73f2178e2 100644 --- a/devscripts/generate_aes_testdata.py +++ b/devscripts/generate_aes_testdata.py @@ -30,6 +30,10 @@ r = openssl_encode('aes-128-cbc', key, iv) print('aes_cbc_decrypt') print(repr(r)) +r = openssl_encode('aes-128-cfb', key, iv) +print('aes_cfb_decrypt') +print(repr(r)) + password = key new_key = aes_encrypt(password, key_expansion(password)) r = openssl_encode('aes-128-ctr', new_key, iv) diff --git a/test/test_aes.py b/test/test_aes.py index 78a28751b..02606eccc 100644 --- a/test/test_aes.py +++ b/test/test_aes.py @@ -8,7 +8,7 @@ import sys import unittest sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) -from youtube_dl.aes import aes_decrypt, aes_encrypt, aes_cbc_decrypt, aes_cbc_encrypt, aes_decrypt_text +from youtube_dl.aes import aes_decrypt, aes_encrypt, aes_cbc_decrypt, aes_cbc_encrypt, aes_cfb_decrypt, aes_decrypt_text from youtube_dl.utils import bytes_to_intlist, intlist_to_bytes import base64 @@ -41,6 +41,13 @@ class TestAES(unittest.TestCase): encrypted, b"\x97\x92+\xe5\x0b\xc3\x18\x91ky9m&\xb3\xb5@\xe6'\xc2\x96.\xc8u\x88\xab9-[\x9e|\xf1\xcd") + def test_cfb_decrypt(self): + data = bytes_to_intlist( + b"\x03\xc7\xdd\xd4\x8e\xb3\xbc\x1a*O\xdc1\x12+8A\xbe\xa2hC\x90\xc4[t" + ) + decrypted = intlist_to_bytes(aes_cfb_decrypt(data, self.key, self.iv)) + self.assertEqual(decrypted, self.secret_msg) + def test_decrypt_text(self): password = intlist_to_bytes(self.key).decode('utf-8') encrypted = base64.b64encode( diff --git a/youtube_dl/aes.py b/youtube_dl/aes.py index c5bb3c4ef..b0ef2ac38 100644 --- a/youtube_dl/aes.py +++ b/youtube_dl/aes.py @@ -88,6 +88,32 @@ def aes_cbc_encrypt(data, key, iv): return encrypted_data +def aes_cfb_decrypt(data, key, iv): + """ + Decrypt with aes in ciphed feedback mode + + @param {int[]} data cipher + @param {int[]} key 16/24/32-Byte cipher key + @param {int[]} iv 16-Byte IV + @returns {int[]} decrypted data + """ + expanded_key = key_expansion(key) + block_count = int(ceil(float(len(data)) / BLOCK_SIZE_BYTES)) + + decrypted_data = [] + previous_cipher_block = iv + for i in range(block_count): + block = data[i * BLOCK_SIZE_BYTES: (i + 1) * BLOCK_SIZE_BYTES] + block += [0] * (BLOCK_SIZE_BYTES - len(block)) + + encrypted_vector = aes_encrypt(previous_cipher_block, expanded_key) + decrypted_data += xor(block, encrypted_vector) + previous_cipher_block = block + decrypted_data = decrypted_data[:len(data)] + + return decrypted_data + + def key_expansion(data): """ Generate key schedule